Zoom imaging systems are well known. In zoom imaging systems, the system's magnification may be varied, thereby allowing flexibility in imaging a scene. For example, if a close-up view of a small portion of the scene is desired, the magnification may be set to a large value, thereby allowing the imaging system to focus on the small scene portion. On the other hand, if an image of the entire scene is desired, the magnification may be set to a small value, thereby allowing the imaging system to capture the entire scene. Zoom imaging may be achieved using optical zoom techniques, digital zoom techniques, or both.
Conventional optical zoom techniques vary the position and/or configuration of imaging system optics, thereby varying magnification and associated field of view. For example, in some conventional cameras, magnification is varied by changing position of optics relative to an image sensor. Image resolution typically remains substantially unchanged as magnification changes, and optical zoom techniques may therefore generate high resolution images across a range of magnification. However, conventional optical zoom techniques normally require moving parts, which is a significant drawback, because moving parts typically (1) add to the imaging system's size, (2) increase the imaging system's cost and complexity, and/or (3) reduce the imaging system's reliability.
Digital zoom techniques, on the other hand, crop an original image down to a desired portion, and then enlarge the cropped image to the same size as the original image. Thus, digital zoom techniques do not require use of moving parts. However, the zoom image will have a lower resolution than original image. While interpolation may be used to increase the resolution of the zoom image, interpolation cannot add information that is missing from the zoom image. Therefore, digital zoom techniques generally suffer from image quality degradation at narrow-zoom levels.
Wafer-level fabrication techniques have been developed to mass produce imaging systems. These techniques typically include forming a large number of image sensors, such as complementary metal oxide semiconductor (CMOS) image sensors, on a single substrate. Respective optics are then disposed on each image sensor to form an assembly including a plurality of imaging systems, which may be subsequently divided into a number of smaller assemblies of one or more imaging systems. Passivation material may be applied before and/or after division of the assemblies. These wafer-level fabrication techniques may allow a large number of imaging systems to be cost-effectively produced.